The term “Tele-operation” refers to the remote operation of a device or system. FIGS. 1 and 2 schematically illustrate typical systems for tele-operation of a remotely piloted vehicle (RPV), such as a so-called “drone”. In the example of FIG. 1, a user-operated remote control unit 2 establishes and maintains a direct radio link 4 with the RPV 6. The user may input control commands to the remote control unit 2, which operates to transmit these commands to the RPV 6 via the radio link 4. A receiver unit (not shown) in the RPV 6 detects the transmitted commands, and supplies them to a local controller unit (not shown) configured to control the various functions of the RPV 6.
As is known in the art, the arrangement of FIG. 1 is typical of low-cost RPV systems of the type commonly sold to hobbyists. While these systems are very inexpensive, they suffer from limited range and (often) low bandwidth through the radio link 4. In addition, problems can arise in situations in which more than one RPV 6 is being operated at a given time, due to radio interference between the involved remote control units 2 and RPVs 6. This radio interference problem is compounded in cases where the radio link 4 is bi-directional so that an RPV 6 can transmit information (such as video images) to its remote control unit 2. The system of FIG. 2 attempts to overcome these limitations by using the Radio Access Network (RAN) 8 to provide the data link between the user and the RPV 6.
As may be seen in FIG. 2, the RAN 8 includes one or more radio transceiver sites 10, each of which incorporates an antenna array 12 and a base station 14. The RAN 8 is normally connected to a data transport network 16 (such as, for example, an Optical Transport Network (OTN)) via one or more gateway servers 18. In the arrangement of FIG. 2, the user may use an application installed on a mobile device 20 (such as a mobile phone, tablet computer or the like) to interact with the RAN 8 to establish a data link 22 between the mobile device 20 and the a transceiver (not shown) in the RPV 6. User input commands can thus be transmitted from the user's mobile device 20 to the RPV 6 via the datalink 22, and information (such as video images) may be transmitted from the RPV 6 back to the user's mobile device 20 for display and storage.
The data link 22 between the user's mobile device 20 and the transceiver of the RPV 6 is supported by a pair of respective connections 24, 26 established between each of the two devices and a Rendezvous Point (RP) 28, which is normally located in the data/transport network 16. The RP 28 can then operate to forward data traffic flows between the two connections, and thus between the two devices, and may also provide Network Address Translation (NAT) to allow the connections 24, 26 to traverse network domains as needed and firewall services to ensure the integrity of the connections.
The arrangement of FIG. 2 is advantageous in that the high bandwidth and strong interference management capabilities of the RAN 8 enable richer data exchange between the user's mobile device 20 and their RPV 6 while also allowing multiple RPV's to operate simultaneously. In addition, the range of the data link 22 between the user's mobile device 20 and their RPV 6 is limited only by the coverage area of the RAN 8. Both of these factors can improve the performance and safety of RPVs. However, this system suffers a limitation in that the extended connections 24 and 26 between the RP 28 and each of the user's mobile device 20 and their RPV 6 increases signal latency. In some cases, the latency can amount to as much as 20 mSec or more. This latency is a problem because it operates on both legs of the round-trip control loop between the 's mobile device 20 and their RPV 6 (i.e. a video image is transmitted from the RPV 6 to the user's mobile device 20; in response to the video image, the user inputs a control command into their mobile device 20 which transmits the command to the RPV 6, which detects and acts upon the command), such that the round trip control delay is increased by an amount approximately equal to double the signal latency. As will be appreciated, a round trip control delay of 40 mSec or more can detrimentally affect the user's ability to control their RPV 6 in a safe and effective manner.
Accordingly, it would be desirable to enable tele-operation in which the high bandwidth and interference management capabilities of the RAN are obtained, while minimizing signal latency.